1. Field of the Invention
This invention relates generally to wireless telecommunications. More particularly, it relates to wireless telecommunication protocol conversion to Voice Over Internet Protocol (VoIP) protocol and vice versa. Specifically, ANSI-41 J-STD-036 E3 interface to VoIP NENA 08-001 V2 interface and vice versa. As well as, GSM J-STD-036 Lg/Lg+ interface to VoIP NENA 08-001 V2 interface and vice versa.
2. Background of the Related Art
Voice Over Internet Protocol (VoIP) is a technology that has been developed as an alternative packet-based telephony technology to the conventional switched telephony service (e.g. PSTN). VoIP takes advantage of high speed Internet data networks, and is able to provide low cost telephony services to end users. VoIP technology emulates a phone call, but instead of using a circuit based switched system such as the telephone network, utilizes packetized data transmission techniques most notably implemented in the Internet.
VoIP phone calls are routed to a VoIP voice gateway, from which they are passed on to their destination VoIP device. Conventional VoIP voice gateways (i.e., soft switches) are typically located in only a few places across the country. A soft switch is a programmable network switch that can process the signaling for all types of packet protocols. Also known as a ‘media gateway controller,’ ‘call agent,’ or ‘call server,’ such devices are used by carriers that support converged communications services by integrating signaling system No. 7 (SS7) type switched telephone signaling with packet networks. Softswitches can support, e.g., IP, DSL, ATM and frame relay.
Because VoIP is Internet Protocol (IP) based, call related information such as CallerID type services may not be available or accurate. A location of a given VoIP device may be statically provisioned to be at a given geographic location, or queried from a home location register (HLR) in a mobile system.
911 is a phone number widely recognized as an emergency phone number that is routed to emergency dispatch personnel and used to determine a location of a caller. Enhanced 911 (E911) is defined by the transmission of callback number and location information to the relevant public safety answering point (PSAP). A PSAP is the endpoint of an emergency services call. PSAPs are responsible for answering emergency services calls. E911 may be implemented for landline and/or mobile devices. Some Public Safety Access Points (PSAPs) are not enhanced, and thus do not receive the callback or location information from any phone, landline or mobile.
The problem is not necessarily solved with the use of a centralized emergency call center. In such case, when a VoIP customer places an emergency call such as an E911 call, the call may be routed to an emergency call center that is very far away, and in some instances half-way across the world to reach the centralized emergency call center. The VoIP E911 call must then be transferred to the relevant 911 center (public safety access point (PSAP)). However, this transfer must take place over the Public Switched Telephone Network (PSTN) because such transfer cannot conventionally be gained to the PSAP's existing Enhanced 911 (E911) dedicated network where location and callback number of the originating 911 caller are provided. Moreover, note that even the call related information (e.g., CallerID) provided with the call would relate to the identity and location of the centralized call center—not to the callback number and certainly not the location of the customer originally dialing 911.
An ANSI-41 J-STD-036 E3 (“E3”) interface is a time division multiplex (TDM) format that operates at 34.368 Mbps, and supports both Physical Layer Conversion Protocol (PLCP) and direct cell mapping.
A voice over Internet Protocol (VoIP) NENA 08-001 V2 (“V2”) interface is used to request emergency call routing information when the call server/routing proxy/redirect server is a separate element from a VoIP voice over Internet Protocol (VoIP) positioning center (VPC).
Session Internet Protocol (SIP) to ISDN User Part (ISUP) conversion, and ISUP to SIP conversion is somewhat common in the market. But currently, an E3 interface interfaces only with a mobile positioning center (MPC). Similarly, an Lg/Lg+ interface interfaces only with Gateway Mobile Location Centers (GMLCs), and V2 interfaces only with VoIP Positioning Centers (VPCs).